To be quite honest you'd be better off just going direct to Pangolin and buying one. The QM2000 systems hold their value extremely well and I wouldn't expect you to find one on the second hand market at anything below 10% of full retail value.
Quote: "There is a theory which states that if ever, for any reason, anyone discovers what exactly the Universe is for and why it is here it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another that states that this has already happened.”... Douglas Adams 1952 - 2001